In carburetor arrangements in work apparatus such as motor-driven chain saws, blowers, brushcutters, cutoff machines or the like, the carburetor is customarily arranged in a carburetor compartment of the apparatus housing and is tightly secured with threaded fasteners by means of stud bolts on a partition wall between the carburetor and the engine.
German patent publication 3,741,018 discloses such a carburetor arrangement in a motor-driven chain saw. The end of the carburetor which faces away from the partition wall is fixed additionally with an attachment piece of sheet metal. This piece of sheet metal functions to fix the filter element of the intake air filter at the same time by means of an attachment screw. The intake air filter is connected at the end of the carburetor facing away from the partition wall to the intake channel section and is fixed tightly to the housing. A carburetor arrangement of this kind is complex and is difficult to assemble and disassemble. To disassemble the carburetor, the attachment sheet metal has to be loosened and the nuts threadably engaging the stud bolts must be removed. The stud bolts are made of metal because of the acting forces whereby a certain heat transfer from the engine to the carburetor must be accepted.
An unwanted warming of the carburetor can, however, lead to the formation of vapor bubbles in the fuel-filled chambers which, in turn, can lead to operational disturbances because of a leaning of the mixture supplied to the engine.
It is an object of the invention to provide a simple carburetor arrangement which can be assembled and disassembled essentially without work tools.
The carburetor arrangement of the invention is for a work apparatus with an internal combustion engine having an inlet channel. The carburetor arrangement includes: an apparatus housing defining a space for mounting the engine therein; a carburetor having an intake channel extending therethrough and the intake channel defining a longitudinal axis; a partition wall disposed between the engine and the carburetor and the carburetor being positioned on the partition wall; the intake channel having a first end facing toward the partition wall and a second end facing away from the partition wall; a connecting tube projecting through the partition wall to connect the inlet channel of the engine to the intake channel of the carburetor at the first end thereof; an intake air filter communicating with the second end of the carburetor for conducting combustion air thereto; an additional wall; and, means for clamping and holding the carburetor between the partition and additional walls in the direction of the longitudinal axis.
The invention is based on the basic idea to fix a carburetor, which is to be mounted on an engine, by clamping the carburetor between two walls fixed in the housing without separate attachment elements.
The carburetor is advantageously pressed against the partition wall between the engine and the carburetor in that the carburetor is loaded by an additional wall with a clamping force.
The additional wall is preferably a wall of the intake air filter housing which can be clipped on the apparatus housing without separate attaching means. For this purpose, the air filter housing is pivotally hooked into a mounting location fixed with respect to the housing and is latched fixedly to the housing via a latch connection which latches in the mounted position. In further embodiments of the invention, the latching is achieved via a tension spring or a threaded fastener connection.
The air filter housing is advantageously held in the mounted position via a pivot arm so that the mounted position can be provided fixed to the housing at a suitable location of the work apparatus independently of the mounting arrangement of the air filter housing. The latching arrangement is advantageously formed by a simple latch hook, which can engage especially behind a latch edge of the partition wall and is provided on the end of a latching arm. Latching can be provided at a suitable location within the housing via the latching arm. Furthermore, considerable clamping forces can be built up via the pivot arm and the latching arm or via the tension spring because of elastic deformation. The clamping forces ensure a secure holding of the carburetor between the partition wall and the air filter housing. For this purpose, the air filter housing, its pivot arm, and the latching arm with the latching hook are made of plastic and are especially made as one piece of plastic.
Centering means, which engage in corresponding centering openings of the carburetor, are mounted on at least one wall in order to ensure a position-correct alignment of the carburetor relative to the connecting pipe, which is held in the partition wall, as well as relative to the flow opening in the air filter housing. The centering means are advantageously provided on both walls between which the carburetor is held. It can be advantageous to provide the centering means for engaging in walls on the carburetor itself.
In a further embodiment of the invention, the carburetor is held by guide bolts on the partition wall. These guide bolts engage in bores of the carburetor. For assembly, the carburetor is threaded onto the guide bolts and is clamped by the air filter housing which is then latched onto the apparatus housing. The carburetor is then reliably held between the wall of the filter housing and the partition wall.
The guide bolts and the partition wall are preferably made as one piece from plastic to avoid a heat conduction between the engine and the carburetor.